Gas lift valve

ABSTRACT

A gas injection valve having a thin-wall, annular valve cage with the operative valve components formed in the valve wall. In the concentric form of the valve, the central flow passage of the valve is coaxial with the central flow passage of a conventional tubing string and has approximately the same internal diameter as the tubing in the string. The external diameter of the valve corresponds substantially to that of a conventional connecting coupler employed in a tubing string to contribute to the thinwalled valve construction which permits unrestricted well operations conducted internally or externally of the valve. Gas flow through an injection passage extending between the central flow passage and the external valve surface is controlled by a resilient tubular control sleeve which selectively engages an annular valve seat. A pressurized fluid contained in an hydraulic linkage chamber extending behind the control sleeve biases the sleeve into engagement with the seat. The hydraulic fluid pressure is regulated by the combined forces of a coil spring and pressure induced forces acting on an axially movable tubular piston forming part of the hydraulic chamber. The force exerted by the spring may be adjusted by altering its compression with opening of the valve being dependent upon the combined effects of internal and external valve pressures, and the force exerted by the spring. A check valve in the flow passage prevents reverse flow through the valve wall. Production of well fluids may be effected either through the associated production tubing or, by appropriate modification, the production tubing may be employed to supply lift gas for production through another conduit such as the well casing. The tool may be modified for side mounting externally of a tubing string.

Thomas R; Alley [72] Inventor ABSTRACT: A gas injection valve having a thin-wall, annular 4002 Fulton, Houston, Tex. 77009 valve cage with the operative valve components formed in the valve wall. 1n the concentric form of the valve, the central flow passage of the valve is coaxial with the central flow passage of a conventional tubing string and has approximately the same internal diameter as the tubing in the string. The external diameter of the valve corresponds substantially to that of a conventional connecting coupler employed in a tubing string to contribute to the thin-walled valve construction which per- 0. 77 99 ll 9 7 3 v. w au 311 o. d N k .1 n Pme flm APP. .111 I125 224 1.11

[54] GAS LIFT VALVE 17 Claims, 8 Drawing Figs. [52] us; 166/224, mils ope'atimls internally or [37/155, 1371525 ternally of the valve. Gas flow through an injection passage ex- [51] Int. tending between the Central flow Passage and the external valve surface is controlled by a resilient tubular control sleeve 501 ram 01 b s/5 4 which Selectively engages an annular valve seat. A pressurized 37 fluid contained in an hydraulic linkage chamber extending behind the control sleeve biases the sleeve into engagement with the seat. The hydraulic fluid pressure is regulated by the com- [56] References Cited UNITED STATES PATENTS bined forces of a coil spring and pressure induced forces acting on an axially movable tubular piston forming part of the hydraulic chamber. The force exerted by the spring may be Cummings........'............

adjusted by altering its compression with opening of the valve being dependent upon the combined effects of internal and external valve pressures, and the force exerted by the spring. A check valve in the flow passage prevents reverse flow through the valve wall.

1 v s i 1 r v a .m a "N 0" h m 3 mm CTG 3667 .6666 9999 11.11. 2028 1.1 4880 9304 2 7743 7793 0223 3333 3/1953 Lee 6/1953 Cummings 5/1956 Grove...........................

Production of well fluids may be effected either through the associated production tubing or, by appropriate modification, the production tubing may. be employed to supply lift gas for production through another conduit such as the well casing.

3/1959 Cummings.................... 043 9/1960 Canalizo... 511 Canalizo.......................

Primary xaminer-.Iames A. Leppink Attomey-Carlos A. Torres v v r w i I The tool may be modified for side mounting externally of a tubing string.

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PATENTED JUL27 I971 SHEET 1 OF 3 M m c A M T 1- -v i. .J 5 A/ i d w T Wall:

THOMAS P. ALLEY (la/9w A.T0'UIMJ ATTORNEY e G w m n A. a 3 w My f r L f i \i fiaufiflfi7l d lwl k A/% //7/// Ill. a a

PATENTED JuLz? l9?! SHEET 3 BF 3 W A W A T7 ORNE Y GAS LIFT VALVE BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to means for recovering petroleum fluids from a subsurface formation. More specifically, the present invention relates to a gas lift valve for use in a completed petroleum well for automatically injecting gas into acolumn of petroleum fluids to assist in elevating the fluids to the surface of the well.

Gas lifting of production fluids from a completed petroleum well is commonly employed when the well formation pressure falls below that required to efficiently lift the production fluid to the well head. Gas lift techniques are also employed in flowing wells where the flow rate of the fluid is undesirably low resulting in only limited production.

Where production through a tubing string is desired, pressurized gas is admitted into the annular space between the well casing and the tubing. Gas lift valves positioned at spaced locations in the tubing string automatically open to inject the gas into the production fluid contained in the tubing when the casing and/or tubing pressures reach predetermined values. The gas entering the production tubing string reduces the weight per unit volume of the fluid making the fluid column lighter" and thus permitting the formation and casing pressures to cooperate in elevating the fluid to the well head. 7

Where production through the casing or other well conduit is desired, pressurized gas is admitted into the tubing string and injected through the gas lift valves into the production fluid contained within a communicating well conduit.

2. Brief Description of the Prior Art Many of the valves customarily employed in gas lift operations have been designed to open when the injection gas pressure exceeds some predetermined minimum. In many of such valves, opening of the valve is largely independent of tubing pressure and is determined primarily by the pressure of the injection gas. It has been recognized that improved gas lift results may be achieved by appropriate modification of the valve whereby opening of the valve is dependent not only upon the pressure of the injected lift gas but also upon the pressure of the fluids contained in the conduit through which production is to be accomplished.

Many of the prior art attempts to provide a valve which is sensitive to production fluid pressure (normally called a fluid sensitive valve) have involved elaborate, and complex mechanisms which are unsatisfactory from the standpoint of their reliability and the large expense associated with their manufacture. In addition, many of such valves are large and cumbersome and provide undesirably large radial dimensions which interfere with many well operations.

In a typical gas lift system, it is necessary to employ a series of valves in a production string with each of the valves being set to open under different pressure conditions. This requirement is imposed largely because the pressure of both the injection gas and the production fluid vary along the length of the well, generally increasing with increasing depths. In addition, the pressure conditions of the well are also changeable with time, due primarily to changes in the formation pressures as the well is produced. From the foregoing, it will be understood that it is undesirable for any of the valves to be open when there is no fluid in the production conduit at the level of the valve or when the fluid column above the valve is so low that very little lift will be accomplished from injection of the gas at that point. On the other hand, it is evident that undesirably large gas pressures would be required to inject the gas into the production fluid at the lower levels in the well where the fluid pressure is extremely high.

In valves sensitive only to casing pressure, the valve will open irrespective of tubing pressure whenever the casing pressure reaches and exceeds a predetermined minimum value. This is, of course, an undesirable characteristic since as previously noted, opening of the valve may vent the lift gas into an empty production string with no lifting of fluids and the loss of injection gas pressure.

In addition, it is also desirable to control the rate of injection as well as the pressure conditions required for injection of the gas. Thus, under conditions of constant flow, it is desirable that the gas be injected into the tubing string at rates which are sufficient to elevate the fluid at the optimum rate with minimum gas pressures. Such constant flow conditions are also desirable at variable rates thus requiring a valve having the ability to throttle. In other instances, it may be desirable to provide periods of intermittent flow with opening being effected only when the injection gas pressure exceeds a predetermined value and the tubing pressure is above a predetermined minimum. Under all other pressure conditions, it would be desirable to maintain the valve in a closed position.

As previously mentioned, conventional fluid operated valves have been undesirably cumbersome, occupying large volumes within the well and have been expensive to construct and maintain and have been unreliable in operation. In the way of example, the prior art has disclosed various pressurized gas chambers which are employed to bias a closure member with valve opening being regulated by the combined effects of both the fluid and the injected gas pressures. In many of the gas charged chambers employed in such prior art valves, 0- rings which are required for forming the requisite seals are constantly subjected to relaxation and roll caused by chamber fluctuations which eventually damages the O-rings and permits leakage of the pressurized gas from the chamber. Thus, periodic and frequent repair and replacement of valves of the type described are required. In addition, the pressure of the gas employed in such gas charged chambers varies with the temperature of the well, which in many cases can be as high as 300 F. or higher. Thus, regulation of the valve becomes difficult and unpredictable and valve opening is subject to large variation dependent upon temperature conditions in the well.

SUMMARY OF THE INVENTION The gas lift valve of the present invention includes a tubular valve cage with thin-walled construction permitting ready access both internally and externally of the valve. The concentric form of the valve is adapted to be connected into a tubing string with the internal diameter of the valve approximately equal the internal diameter of a standard tubing string. Additionally, the outer diameter of the valve is designed to be approximately equal to that of the outer diameter of a standard coupling member employed to join tubing members together in a production string. By virtue of the described design, the internal and external radial dimensions of the valve of the present invention are substantially equal to the corresponding dimensions of the tubing string and connecting collars so that the valve may be inserted into a tubing string without restriction of the internal flow passage of the tubing or of the external configuration of the tubing, thus permitting the free use of tools which must pass through the center of the tubing bore or pass externally of the tubing string.

The valve of the present invention is sensitive to the pressure of the production fluid in the well conduit, with opening and closing of the valve being primarily dependent upon the production fluid pressure rather than the injection gas pressure. This pressure sensitivity is accomplished without the use of a charged gas chamber thus eliminating temperature related pressure variation and also avoiding the difficulty associated with leakage of gas from such chambers. In both the concentric and side mounted forms of the valve, a coil spring which is substantially insensitive to temperature variations is employed to exert a force against an axially movable piston which in turn pressurizes an hydraulic linkage chamber to bias an annular, resilient sleeve closure member toward an annular valve seat. The strength and size requirements of the spring are significantly reduced by employing axially spaced, different size sealing areas on the piston which are acted upon by the pressure within the valve body to create a resultant axially directed force tending to decrease the pressure of the hydraulic linkage fluid. The force exerted by the spring employed in the valve is adjustable to permit presetting of the valve so that it opens only when a predetermined pressure relationship exists between the production fluid, the injection gas and the set pressure of the valve.

The hydraulic linkage which effectively conveys the spring and piston forces to the sleeve extends behind the annular resilient closure member of the valve to provide a constant, uniformly distributed closure force tending to provide an effective sealing engagement with the annular valve seat even after prolonged usage and partial wear of the seat.

In a modified form of the valve of the present invention, the valve is adapted to be externally mounted along the side of a tubing string. The basic operation and construction ofthe side mounted version of the valve is essentially similar to that of the concentric form ofthe valve.

The foregoing features and advantages of the valve of the present invention will be better understood from the following descriptions and the related drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial elevation illustrating the concentric form of the valve ofthe present invention connected into a standard production tubing string;

FIGS. 2A and 2B illustrate the top and bottom portions respectively of the concentric form of the gas lift valve of the present invention in longitudinal sections;

FIG. 3 is a horizontal cross section taken along the line 3-3 of FIG. 2A;

FIG. 4 is a detailed showing of the concentric form of the gas lift valve illustrating the gas injection flow passage in open position;

FIG. 5 illustrates a modified form of the concentric valve adapted for injection of gas from the valve into the annulus of the well for production through the casing;

FIG. 6 illustrates another form of the concentric valve adapted for production through the casing;

FIG. 7 illustrates a modified, side-mounted form of the gas lift valve of the present invention in position in a standard production tubing string;

FIGS. 8A and 8B illustrate the top and bottom portions, respectively, of the side-mounted form of the valve in longitudinal section; and

FIG. 9 illustrates a horizontal cross section taken along the line 9-9 ofFIG. 813.

DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to FIG. 1, the concentric form of the gas lift valve of the present invention, indicated generally at 10, is illustrated in a production tubing string T disposed within a cased well bore. Valve 10 is connected into the string T by means of conventional, internally threaded collars or coupling members M which connect externally threaded pins formed at the ends of the valve 10 and at the ends of the tubing sections in the string T. In one form of the invention, the annular space A (annulus) between the well casing C and the tubing string T is provided with a suitable gas which is maintained at a pressure exceeding the pressure existing within all or specified portions of the production tubing string T. The basic function of the valve 10 is to inject the relatively high pressure casing gas in the annulus A into the lower pressure tubing flow passage extending through the tubing string T for the purpose oflifting the production fluid contained within the tubing to the wellhead.

FIGS. 2A and 2B illustrate the upper and lower portions respectively of a preferred embodiment of the concentric form ofthe gas lift valve 10 ofthe present invention. The valve I0 includes a composite tubular body which is provided with externally threaded upper and lower pin connections adapted to threadedly engage internal threads formed on the couplings M. A central flow passage 13 extends axially through the center of the valve 10 and communicates with the coaxial central flow passage of the tubing string T.

The composite tubular body of the valve 10 includes a valving section 14, an hydraulic linkage section 15, and a regulating section 16 at the upper, central and lower portions respectively of the valve body. In general terms, the valving section 14 functions to selectively open an injection passage extending through the tubular wall of the valve 10 to inject high pressure casing gas from the annulus A into the flow path 13 formed internally of the valve. The injection passage of the valve I0 is designed to open automatically whenever the sum of the tubing pressure and casing pressure exceeds a predetermined value. Where production through the tubing T is desired, the injection passage is also designed to automatically close to prevent reverse flow when the sum of the tubing pressure and casing pressure exceeds the predetermined value but the tubing pressure is greater than the casing pressure. The specific pressure value required for opening of the injection passage may be selected by adjustment of the regulating section 16 which acts through the hydraulic linkage section 15 to effect the required control in the valving section 14.

The valve 10 is preferably constructed from several cooperating components having the general form illustrated in FIGS. 2A and 2B. The valve components include a first body member 17 having external threads 17a formed along its upper end which engage the collar M to connect the top of the valve into the tubing string T. A second body member I8 which telescopes over the member 17 is threadedly engaged with the threads 17a and extends downwardly along a portion of the member 17 where it engages a third tubular body member 19. A forth tubular body member 20 is threadedly secured to the lower end of body member 17 and internal threads 20a formed along the lower end ofmember 20 engage a fifth body member 21. The member 21 is provided with external threads 21a which engage internal threads formed in a collar M to connect the lower end of tool 10 into the tubing string T.

An axially movable, tubular piston member 22 positioned within the tool 10 engages and is adapted to move axially along smooth internal cylindrical surfaces 17b and 20b formed within the body members 17 and 20 respectively. The lower end of piston 22 is seated in a rim 23a formed at the top of a tubular sleeve 23 with the body of the sleeve downwardly from the rim through the center of a coil spring 24. The upper end of the spring 24 bears against a shoulder formed below the rim 23a and the lower end of the spring 24 engages and is supported by an axially movable adjustment bushing 25 to maintain the spring in compression. The outer circumferential surface of bushing 25 is threadedly mounted in the threads 20a and the central bore of the bushing slidingly engages and guides the outer tubular surface of sleeve 23. From the illustrated construction, it will be appreciated that rotation of the bushing 25 upwardly through the threads 20a increases the compression of the spring 24 and biases the sleeve 23 and piston 22 upwardly.

Referring to FIG. 2A, the valving section 14 includes an injection passage indicated generally at 30 extending through the tubular body of the tool 10. The passage 30 is formed from a series of interconnected passages including radial bores 30a which extend through body member 18 and connect with an annular space 30b formed between the body members 17 and 18. An annular closure member 29 constructed of rubber or other suitable material is secured along its upper end to the internal surface of body member 18 and its lower end selectively engages the external surface of body member 17 to form a one-way flow check valve.

With joint reference to FIGS. 2A and 3, it may be seen that the injection passage 30 further includes two downwardly extending passages 30c which are formed by milling flat surfaces along a portion of the cylindrical outer surface of body member I7. The injection passage 30 is completed by a second set of similarly milled surfaces forming passages 30d which extend downwardly to upwardly directed bores e extending through the wall of body member 17.

The nonmilled cylindrical portion of body member 17 separating passages 30c and30d forms a valve seat 170 which cooperates with a resilient, tubular valve closure member 31 constructed of rubber or other suitable material to form a control valve. The upper end of closure member 31 is bonded or otherwise suitably secured to a metal retaining ring 32 fixed to the tubular body member 19 by set screws 33 or any suitable means. The lower end of closure member 31 is also bonded or otherwise suitably connected to a second metal retaining ring 34 which in turn is rigidly secured to body member 17 by pins or other suitable securing means.

The hydraulic linkage 15 includes a plural-part fluid chamber having a first annular chamber 40a confined between the internal surface of body member 19 and the combined external surfaces of closure member 31, retaining ring 34 and body member 17. A radial bore 40b extends through the wall of body member 17 to connect annular chamber 40a with a second annular chamber 400 formed between body member 17 and piston 22. Hydraulic fluid confined within the fluid chamber 40 is prevented from leaking from the chamber by resilient O-rings 41, 42, 43, 44, and 46 constructed of rubber or other suitable material. A filler cap 40 is threadedly engaged within a tapped radial bore formed in body member 17 to permit the chamber 40 to be charged with a suitable hydraulic fluid.

O-rings 42 and 43 are adapted to form. a sliding seal between the piston 22 and the internal cylindrical surfaces 20b and 17b respectively to permit axial movement of the piston through the surrounding body members. O-ring 42 also cooperates with a second O-ring 47 which slides along the outer cylindrical surface 22a of the piston 22 to form an air chamber 48 between the piston 22 and body member 20. As will be more fully described hereinafter, the chamber 48 cooperates with the regulating and linking sections 16 and 15 respectively to join in establishing the pressure required for opening the control valve in injection passage 30.

An O-ring 49 is disposed between body member 18 and retainer ring 32 to prevent leakage of gas or fluid from passage 300 in the event of reverse flow conditions with check valve closure member 29 closed. As will be more fully explained, the check valve member 29 prevents reverse flow from the passage 13 into the annulus A when control valve member 31 is open but tubing pressure exceeds casing pressure. A final O- ring is disposed between body members 20 and 21 to prevent leakage between the internal flow passage 13 and the annulus A.

The operation of the concentric gas injection valve 10 of the present invention may best be described by joint reference to FIGS. 2A and 4. When the casing gas pressure in the annulus A is greater than the pressure of the production fluid in the flow passage 13, and the sum of the casing and tubing pressure exceeds a predetermined minimum value, the casing gas travels through the radial bores 30a to the annular passage 30b and forces the check valve sleeve 29 away from the body member 17. The casing gas then flows past the check valve into the two chambers 300 where the pressure of the gas is exerted against the control valve closure member 31 tending to open the control valve by pushing member 31 radially outwardly away from the valve seat 17cv The tubing pressure in chamber 30d on the lower side of valve seat 170, also exerts a radially outwardly directed opening force against the closure member 31 and the combined pressure induced opening forces exerted against the closure member 31 are transmitted to the overlying hydraulic fluid in chamber 40a. Sufficient pressure exerted against the member 31 causes displacement of the fluid in chamber 400 which produces an axially downwardly directed force on the piston 22 to overcome the upwardly directed force exerted by the combined effects of the coil spring 24 and the tubing pressure acting on the piston 22. The downward movement of the piston 22 increases the volume of the lower portion 40c of chamber 40 to accommodate the fluid displaced by the closure member 31. As the closure member 31 thus displaces part of the fluid in chamber 400, it moves radially outwardly away from the valve seat 17c to fully open the injection passage 30. Full opening of the check valve member 29 and control valve member 31 is illustrated in FIG. 4.

With the injection passage 30 open as illustrated in FIG. 4, casing gas from annulus A continues to enter the central valve flow passage 13 until the pressure in injection passage 30 and the tubing pressure fall below that required to keep closure member 31 away from the valve seat 170. The illustrated design of the valve 10 is such that control valve closure member 31 remains open when a predetermined pressure exists in passage 30 irrespective of whether the tubing or casing has the highest pressure. The check valve closure member 29 automatically closes to prevent reverse flow or fluid or 'gas through the injection passage 30 when the pressure in flow passage 13 exceeds that of the gas in annulus A. The check valve is thus effective to prevent production fluid in the valve passage 13 from being ejected into the annulus A when casing pressure unexpectedly falls or when high pressures unexpectedly occur in the production string or when the valve 10 has been improperly set for the existing well conditions.

The pressure required to open control valve closure member 31 may be adjusted by axial adjustment of the bushing 25 which alters the force exerted by spring 24 against the piston 22. The bushing 25 is adjusted by rotating it with the assistance of a suitable tool which is adapted to engage slots 25a formed in the base of the bushing. It will be understood that the desired adjustment of bushing 25 is preferably done before mounting the valve 10 in the tubing string with the body member 21 being removed from body member 20 to provide access to the bushing.

As previously indicated, the total casing and tubing pressure required for opening closure member 31 is increased by advancing the bushing 25 upwardly through the surrounding valve body member 20 to increase the force exerted by the spring 24 against the piston 22 which in turn increases the pressure of the hydraulic fluid in the linkage chamber 40. As the pressure of the fluid in chamber 40 increases, the control valve closure member 31 is forced radially inwardly against the valve seat 17c with greater force. It will be understood that the reverse adjustment of bushing 25 in a downward axial direction through the surrounding body 20 decreases the compression of spring 24 and reduces the pressure induced force required for opening control valve closure member 31.

With reference to FIG. 2A it may be seen that the valve 10 is designed whereby the sliding sealing areas along O-rings 42, 43 and 47 are of unequal size. Thus the outside diameter of O- ring 42 and the diameter of its associated sealing surface 20b are larger than the outside diameter of Oring 43 and its associated sealing surface 17b which in turn are larger than the internal diameter of O-ring 47 and its associated sealing surface 22a. By virtue of the difference in sealing surface areas, a downward movement of piston 22 increases the volume of hydraulic chamber 40 which in turn reduces the pressure of the fluid in the chamber. On the other hand, an upward movement of the piston 22 reduces the total volume in the hydraulic chamber which increases the pressure of the fluid.

The unequal cross-sectional areas along O-rings 43 and 47 cooperate with the effect of the air chamber 48 to play an important part in the operation of the gas lift valve 10 of the present invention in that they cooperate to reduce the amount of force which must be exerted by the spring 24 to produce the desired closing force exerted by the hydraulic fluid against the outer surface of control valve closure member 31. Since the sliding sealing area of O-ring 43 is larger than that of O-ring 47, the tubing pressure induced force acting on the piston 22 produces a net downwardly directed force. This force cooperates with the spring force to establish the-opening pressures required for opening the control valve closure member 31. Air chamber 48 is preferably kept at approximately atmospheric pressure.

The described relationship of sealing areas and the use of the air chamber 48 permit a relatively small spring to be employed for providing the desired axially directed forces against the piston 22. The use of a relatively small coil spring in the valve 10 increases the valve's inner diameter and decreases it outer diameter to produce a thin-wall concentric valve.

By virtue of the thin-wall construction of the tool 10, it will be appreciated that the internal diameters of body member 17, piston 22, sleeve 23 and body member 21 may be made substantially equal to the internal diameter of the central flow passage employed in a standard tubing conduit. ln addition, the outside diameter of body members 18, 19, 17, 20 and 21 may be made substantially equal to the outside diameter of the conventional or standard couplings M. Thus, it will be evident that the design of the gas lift valve 10 of the present invention permits the valve body to be constructed with internal and external dimensions which do not exceed those of standard tubing and coupling members customarily employed in production strings. Valve 10 thus provides no internal restrictions which would prevent passage of tools or equipment through the center of the tubing string T nor does it provide external obstructions which interfere or otherwise limit the use of washover tools or other external tubing string equipment or devices.

Where production of the well fluid through the casing rather than the tubing T is desired, the valve 10 may be modified by simply reversing the direction of operation of the check valve. As illustrated in H0. 5, a modified check valve closure member 29 is mounted on a body member 19 for closure against the body member 17 when production fluid tends to flow from the annulus into the tubing. It will be appreciated that opening of the modified form ofthe valve 10 illustrated in H0. is essentially unaffected by casing pressure since the control valve closure member 31 is isolated from the casing pressure by the action of closure member 29'. Production through the casing may be accomplished with opening of the gas lift valve being made sensitive to both tubing and casing pressure by securing a single check valve closure member 29" to a retaining ring 34" in the injection passage 30 between the valve seat 17c and the injection bore 30c as illustrated in H0. 6. The structure of the modified forms of the valve illustrated in FIGS. 5 and 6 is the same as that of the valve 10 illustrated in FIGS. 2-4 with the exception of the structure and positioning of the check valve closure members 29' and 29" respectively.

FlGS. 7-9 illustrate a modified form 110 of the gas valve of the present invention designed to be side mounted externally of the tubing string T. The valve 110 is engaged with an adapter sub S which in turn is connected into the tubing string T by suitable coupling members M. The lower end of the valve 110 is threadedly secured within a receptacle R extending from the sub 5 where it connects into a central sub passage P by means ofa channel D.

The sub S includes an overhead, downwardly tapered protection guard G which extends over the top of the valve body 110. The guard G cooperates with the upwardly tapered surface formed under receptacle R to protecttthe valve 110 from tools which are lowered around the sub and to prevent the valve from hanging up as the tubing string T and attached sub S are lowered into a wellbore.

FIGS. 8A and 8B illustrate details in the construction of the valve 110 with the structure illustrated in FIG. 88 being the lower portion of the tool 110 illustrated in H0. 8A. The tool 110 includes a valving section 114, an hydraulic linkage section 115 and a regulating section 116 at the lower, central and upper portions, respectively, of the valve body. The valve body is of a plural-part construction and includes a tubular valve sleeve member 117 secured to internal threads formed within a surrounding tubular body member 118. The body member 118 has externally formed threads [180 formed along its lower portion which are designed to mate with appropriate threads formed within the receptacle R of the sub S. The valve sleeve 117 extends upwardly from the member 118 and is threadedly engaged along its upper end with a surrounding tubular body member 119 which in turn is secured along its upper end to a tubular spring housing 120. The top of the housing 120 is enclosed and sealed by means ofa cap 121 and the housing is internally threaded with threads 120a which extends along a portion ofits length.

An axially movable piston 122, disposed within the body of valve 110, is provided with two sealing areas which form a sliding seal with a cylindrical surface 117a formed internally of the body member 117 and a second cylindrical sealing surface l19a formed internally of body member 119. An elongate rod 123 extends axially through the spring housing 120 through the center of a coil spring 124. The lower end of rod 123 is provided with a T-head 123a which provides a support base for the spring 124. An axially movable, externally threaded adjustment bushing 125 is threadedly engaged with the threads 1200 formed within the housing 120 and provides an upper bearing surface for the spring 124. The bushing 125 is centrally bored to provide support and guidance for axial movement of the rod 123. A metal bearing ball 126 is positioned between the bottom of rod 123 and the top ofa bearing member 127 threadedly engaged to the top of piston 122. The axial end surfaces of the rod 123 and bearing member 127 are provided with conical recessed to retain the bearing ball 126 in position.

The valving section 114 of the valve 110 includes an annular check valve 129 formed of rubber or other suitable resilient material. The base of closure member 129 is bonded or otherwise suitably secured to the body member 118 and the upper portion of the closure member is selectively engageable with the body member 117 to form a one-way-flow check valve within an annular injection flow passage indicated generally at 130. A tubular control sleeve 131 of rubber or other suitable material is positioned within the injection flow passage 130 and held in place by means of an annular retaining ring 132 secured to the lower portion of the closure member 131 and a second annular retaining ring 134 secured to the upper end of closure member 131. The retaining ring 132 is held in position between the outer body members 118 and 119 while the upper retaining ring 134 is secured to the body member 117 by pins 135 or other suitable means.

Injection flow passage 130 is a composite passage way which includes a plurality of radial bores 130a extending through the body member 118 to an annular passage 13012 formed in the space between the external surface of the body member 117 and the internal surface of closure member 129. The injection passage 130 continues by means of an annular passage 130a formed between the outer cylindrical surface of body member 117 and the combined internal surfaces of retaining ring 132 and closure member 131. The closure member 131 engages a valve seat 1176 extending from the valve sleeve 117 to selectively seal off the flow passage 130. When closure member 131 is moved away from the valve seat 1170 to open the flow passage 130, flow of gas is permitted from the annular passage 130a below the valve seat in the annular space between the external surface of valve sleeve 117 and the combined internal surfaces of the retaining ring 134 and closure member 131. Gas in the passage 130d travels downwardly inclined bores 1302 which extend through the valve sleeve member 117 into the internal flow passage ofthe valve 110.

With reference to FIG. 9 which is a cross section taken along the line 9-9 of FIG. 8, it may be seen that the injection flow passage 130C extends continuously around the body member 117 to form a complete annular passage. This construction is to be distinguished form the corresponding passages previously referred to with respect to the concentric form of the valve 10 wherein plural axially extending, nonconnecting passages 30c were formed by milling the corresponding valve section 17.

Referring to the hydraulic linkage section 115 of valve 110, an hydraulic chamber indicated generally at is formed ofa plurality of cooperating, interconnecting chambers which in- 9 cludean annular chamber 140a formed in the space between the internal surface of body member 118 and the' combined external surfaces of closure member 131, retaining ring 134 and valve sleeve 117. A radial bore 14% extends through the body member 117 and; communicates with an annular chamber 1400 formed between the internal surface of sleeve valve member I17 and communicates with an annular chamber [40c formed between the internal surface of sleeve valve member 1 l7 and the external surface of piston 122. The upper end of chamber 1400 communicates througha radial bore 140d "extending through the piston 122 to a central chamber.l40e. It will be appreciated that the removable bearing member 127 secured to theu'pper end of piston 122 permits the chamber 140 to be filled with the desired hydraulic fluid.

The various components of the body of valve 110 are 'threadedly engaged with each other and equipped with suitable O-rings of resilient rubber or other suitable material to seal between the internal cylindrical surfaces 117a and 119a respectively to permit piston 122 to be moved axially changing the pressure of the hydraulic fluid in chamber 140. O-rings 144-150 are'adapted to form stationary seals between the mating components of the valve body respectively associated with each of the o rings.

As with the concentric form of the valve 10, the valve 110 may be adjusted to alter the pressure required for opening or closing of the closure member 131 by appropriate adjustment of the bushing 125 through the internal threads 120a. For this purpose, suitable slots 125a are provided in the bushing 125 to permit a tool to be employed in rotating the bushing 125 through the threads 1200. The compressive force of the spring 124 acts against the T-head 123a and through the bearing ball 'l26a to force the piston 122 in a downward direction.

will'be understood that the greater the force exerted by spring 124, the higher the tubing pressure required for opening injection flow passage 130. Thus, downward axial movement of the bushing 125 corresponds to an increase in opening pressure of the valve and a reverse upward movement, correspondently results in a decrease in theamount of pressure required for valve opening.

In the design of the valve 110, the external sealing area of the O-ring 143 is greater than the external sealing area of O ring 142 and the pressure within housing 120 corresponds substantially to atmospheric pressure. By making the sealing area at O-ring 143 larger than that at O-ring 142, the same pressure acting on both O-rings produces a net downwardly directed force on the piston 122. in the form of the valve 110, two closing forces are exerted against the piston 122, namely the force exerted by spring 124 and the pressure induced force acting at O-ring 143, A single opening force, tubing pressure acting at the member 131 moved away from the valve seat i170, the

casing gas moves past the seat and up intochamber 130d where it flows into the central passage of the valve 110 and exits at the bottom of the passage into the channel D where it then flows to the main flow passage T within the sub S of the tubing string. Reverse flow of fluid through the passage 130 is prevented by the one-way action of check valve closure member 129. It will also be understood that under conditions where it is desired to employ the valve from regulating flow of gas from the tubing string T into the area outside of the tubing string T, the check valve 129 need only be reversed in its action. Where tubing pressure sensitivity is desired, the check valve closure member 129 may be mounted'within annular passage 130d in the manner previously described with reference to valve 10.

From the foregoing it will be appreciated that the present invention provides a thin-walled, temperature invarient, fluid operated valve which will reliably inject gas into the production fluid of a well under regulated, predetermined conditions of fluid and injection gas pressures Moreover, the simple construction and operation of the valve contributes to low construction costs, long life and dependable operation. The design of the valve of the present invention makes port size insignificant in valve operation with the only limitation being that the injection passage must be large enough to prevent undesirable back pressures from developing. The lack of port size criticality is important when compared with various prior art valves where port sizes are an integral part of the valve operation. Additionally, it will be understood that while the foregoing description has pointed out the effects of the injection gas acting against the control valve closure member, the primary opening force effecting valve operation is the pres sure of the production fluid rather than the pressure of the injection gas.

In a continuous flow gas lift, the objective to be obtained is to lower the total weight of the fluid in the tubing by aeration of the flowing fluid column with injected gas rather than the lifting of the fluid to the well head as is the case of intermittent lift. For this reason, in continuous flow gas lift, the injection gas is desirably metered into the tubing at a velocity which is as close as possible to the velocity of the flowing'fluid since extreme differences in velocity will produce slug type flow. The valve of the present invention meets the exacting conditions required for continuous flow in that changes in the flowing pressure and velocity-of the'production fluid are almost instantly transmitted through the spring loaded hydraulic linkage to vary the volume of gas being metered through the valve.

The foregoing disclosure and description of the invention is illustrative and explanatory thereof, and various changes in the size, shape and materials as well as in the details of the illustrated construction may be made within the scope of the appended claims without departing from the spirit'of the-invention.

lclaim:

l. A gas lift valve for injecting gas into the production conduit in a petroleum well comprising:

a. a valve body adapted to be connected with a conduit in a petroleum well; b. passage means extending through said valve body for conveying gas between the internal portion of the conduit and the area externally of the valve body; c. first seal means included in said valve body for opening and closing said passage means;

.biasing means included with said valve body for producing a biasing force for regulating the opening and closing of said first seal means;

e. hydraulic linkage means extending between said biasing means and said first seal means for directly linking the biasing force produced by said biasing means with said first seal means;

f. movable piston means included with said biasing means and disposed within said valve body for altering the pressure of hydraulic fluid in said linkage as said piston moves with respect to said valve; and axially spaced sealing'means having different sized sealing areas included with said piston means for producing an axially directed force induced by the pressure of the fluid or gas in the conduit and exerted against said piston means tending to alter the pressure of said hydraulic fluid in said linkage.

2. The gas lift valve as defined in claim 1 wherein said biasing means further includes adjustable spring means operably connected with said piston means for exerting an adjustable biasing force against said piston means tending to move said piston means axially with respect to said valve body.

3. The gas lift valve as defined in claim 2 wherein said piston means further includes axially spaced gas sealing means having different size sealing areas for forming a gas chamber between said piston means and said valve body.

4. The gas lift valve as defined in claim 2 further including adjustment means for adjusting the biasing force exerted by said spring means.

5. The gas lift valve as defined in claim 2 wherein:

a. said first seal means includes a resilient, tubular closure member surrounding a substantially cylindrical valve seat means;

b. said passage means extends between said tubular closure member and said valve seal; and

c. said hydraulic linkage means includes first fluid filled chamber means extending over the outer circumferential surface of said tubular closure member whereby said fluid may be pressurized to exert a radially inwardly directed force against said tubular closure member to force said tubular closure member into sealing engagement with said valve seat means to close said passage means.

6. The gas lift valve as defined in claim 5 wherein said linkage means further includes:

a. second fluid filled chamber means formed between said piston means and said valve body;

b. fluid filled connecting means connecting said first and second chamber means; and

c. sealing surface means cooperating with said spaced sealing means on said piston means for altering the volume of said second chamber means as said piston means is moved axially with respect to said valve body to alter the pressure ofsaid hydraulic fluid.

7. The gas lift valve as defined in claim 6 further including second seal means for permitting fluid or gas flow through said passage means in one direction and preventing flow in the reverse direction.

8. The gas lift valve as defined in claim 7 further including adjustment means for adjusting the biasing force exerted by said spring means.

9. The gas lift valve as defined in claim 8 wherein said valve body is substantially tubular and includes securing means at each of its axial ends for concentric connection into the well conduit.

10. The gas lift valve as defined in claim 8 wherein said valve body is substantially tubular and includes securing means for side mounted connection into the well conduit.

11. The gas lift valve as defined in claim 8 wherein:

a. said sealing means include O-rings disposed between said piston means and said valve body; and

b. said sealing surface means include different diameter cylindrical surfaces formed internally ofsaid valve body.

12. The gas lift valve as defined in claim 1 wherein said biasing means includes coil spring means coaxially disposed with respect to said valve body.

13. The gas lift valve as defined in claim 12 wherein said valve body is substantially tubular and includes securing means at each of its axial ends for concentric connection into the well conduit.

14. The gas lift valve as defined in claim 1 wherein said piston means further includes axially spaced gas sealing means having different size sealing areas for forming a gas chamber between said piston means and said valve body.

15. The gas lift valve as defined in claim 1 wherein said valve body is substantially tubular and includes securing means for side mounted connection into the well conduit.

16. A gas lift valve for injecting gas into the production conduit in a petroleum well comprising:

a. a valve body adapted to be connected with a conduit in a petroleum well; I b. passage means extending through said valve body for conveying gas between the internal portion of the conduit and the area externally of the valve body;

c. first seal means included in said valve body for opening and closing said passage means;

d. biasing means included with said valve body for producing a biasing force for regulating the opening and closing of said first seal means;

e. hydraulic linkage means extending between said biasing means and said first seal means for directly linking the biasing force produced by said biasing means with said first seal means; and

. coil spring means included with said biasing means and coaxially disposed with respect to said valve body with said valve body being substantially tubular and including securing means at each of its axial ends for concentric connection into the well conduit.

17. The gas lift valve as defined in claim 16 wherein said biasing means further includes adjustable spring means operably connected with said piston means for exerting an adjustable biasing force against said piston means tending to move said piston means axially with respect to said valve body. 

1. A gas lift valve for injecting gas into the production conduit in a petroleum well comprising: a. a valve body adapted to be connected with a conduit in a petroleum well; b. passage means extending through said valve body for conveying gas between the internal portion of the conduit and the area externally of the valve body; c. first seal means included in said valve body for opening and closing said passage means; d. biasing means included with said valve body for producing a biasing force for regulating the opening and closing of said first seal means; e. hydraulic linkage means extending between said biasing means and said first seal means for directly linking the biasing force produced by said biasing means with said first seal means; f. movable piston means included with said biasing means and disposed within said valve body for altering the pressure of hydraulic fluid in said linkage as said piston moves with respect to said valve; and g. axially spaced sealing means having different sized sealing areas included with said piston means for producing an axially directed force induced by the pressure of the fluid or gas in the conduit and exerted against said piston means tending to alter the pressure of said hydraulic fluid in said linkage.
 2. The gas lift valve as defined in claim 1 wherein said biasing means further includes adjustable spring means operably connected with said piston means for exerting an adjustable biasing force against said piston means tending to move said piston means axially with respect to said valve body.
 3. The gas lift valve as defined in claim 2 wherein said piston means further includes axially spaced gas sealing means having different size sealing areas for forming a gas chamber between said piston means and said valve body.
 4. The gas lift valve as defined in claim 2 further including adjustment means for adjusting the biasing force exerted by said spring means.
 5. The gas lift valve as defined in claim 2 wherein: a. said first seal means includes a resilient, tubular closure member surrounding a substantially cylindrical valve seat means; b. said passage means extends between said tubular closure member and said valve seal; and c. said hydraulic linkage means includes first fluid filled chamber means extending over the outer circumferential surface of said tubular closure member whereby said fluid may be pressurized to exert a radially inwardly directed force against said tubular closure member to force said tubular closure member into sealing engagement with said valve seat means to close said passage means.
 6. The gas lift valve as defined in claim 5 wherein said linkage means further includes: a. second fluid filled chamber means formed between said piston means and said valve body; b. fluid filled connecting means connecting said first and second chamber means; and c. sealing surface means cooperating with said spaced sealing means on said piston means for altering the volume of said second chamber means as said piston means is moved axially with respect to said valve body to alter the pressure of said hydraulic fluid.
 7. The gas lift valve as defined in claim 6 further including second seal means for permitting fluid or gas flow through said passage means in one direction and preventing flow in the reverse direction.
 8. The gas lift valve as defined in claim 7 further including adjustment means for adjusting the biasing force exerted by said spring means.
 9. The gas lift valve as defined in claim 8 wherein said valve body is substantially tubular and includes securing means at each of its axial ends for concentric connection into the well conduit.
 10. The gas lift valve as defined in claim 8 wherein said valve body is substantially tubular and includes securing means for side mounted connection into the well conduit.
 11. The gas lift valve as defined in claim 8 wherein: a. said sealing means include O-rings disposed between said piston means and said valve body; and b. said sealing surface means include different diameter cylindrical surfaces formed internally of said valve body.
 12. The gas lift valve as defined in claim 1 wherein said biasing means includes coil spring means coaxially disposed with respect to said valve body.
 13. The gas lift valve as defined in claim 12 wherein said valve body is substantially tubular and includes securing means at each of its axial ends for concentric connection into the well conduit.
 14. The gas lift valve as defined in claim 1 wherein said piston means further includes axially spaced gas sealing means having different size sealing areas fOr forming a gas chamber between said piston means and said valve body.
 15. The gas lift valve as defined in claim 1 wherein said valve body is substantially tubular and includes securing means for side mounted connection into the well conduit.
 16. A gas lift valve for injecting gas into the production conduit in a petroleum well comprising: a. a valve body adapted to be connected with a conduit in a petroleum well; b. passage means extending through said valve body for conveying gas between the internal portion of the conduit and the area externally of the valve body; c. first seal means included in said valve body for opening and closing said passage means; d. biasing means included with said valve body for producing a biasing force for regulating the opening and closing of said first seal means; e. hydraulic linkage means extending between said biasing means and said first seal means for directly linking the biasing force produced by said biasing means with said first seal means; and f. coil spring means included with said biasing means and coaxially disposed with respect to said valve body with said valve body being substantially tubular and including securing means at each of its axial ends for concentric connection into the well conduit.
 17. The gas lift valve as defined in claim 16 wherein said biasing means further includes adjustable spring means operably connected with said piston means for exerting an adjustable biasing force against said piston means tending to move said piston means axially with respect to said valve body. 